Use of circuit breakers is widespread in modern-day residential, commercial and industrial electric systems, and they constitute an indispensable component of such systems toward providing protection against over-current conditions. Various circuit breaker mechanisms have evolved and have been perfected over time on the basis of application-specific factors such as current capacity, response time, and the type of reset (manual or remote) function desired of the breaker.
One type of circuit breaker mechanism employs a thermo-magnetic tripping device to "trip" a latch in response to a specific range of over-current conditions. The tripping action is caused by a significant deflection in a bi-metal or thermostat-metal element which responds to changes in temperature due to resistance heating caused by flow of the circuit's electric current through the element. The thermostat metal element is typically in the form of a blade and operates in conjunction with a latch so that blade deflection releases the latch after a time delay corresponding to a predetermined over-current threshold in order to "break" the current circuit associated therewith.
Another type of circuit interruption arrangement, useful for interrupting circuits having higher current-carrying capacities, uses current transformers to induce a current corresponding to the current in the circuit path, and an electronic circuit monitoring this induced current to detect power faults in the circuit path. In response to a power fault being detected, the electronic circuit generates a control signal to actuate a solenoid (or equivalent device) to cause the circuit-interrupting contacts to separate and interruption of the circuit path. The electronic circuits detecting the faults may or may not employ a microcomputer for flexibility and added intelligence for controlling the switching operations.
Known tripping arrangements do not, however, provide for an effective communications network between the electronic circuit monitoring for faults in the communication line and a central control point. Moreover, known tripping arrangements heretofore have been implemented using relatively large and expensive components.
Accordingly, there is a need for a circuit interruption arrangement which overcomes the aforementioned shortcomings.